1. Field of the Invention
The general purpose of an applicator or brush is to pick up an adequate supply of material, such as mascara, from a container, carry it from the reservoir of the container without dripping, and apply it evenly to the particular area of the body, such as, for example, eyelashes. This needs to be achieved without depositing lumps or blobs of the material on the eyelashes.
To do so, it is important that the bristle ends of the applicator have a distribution that permits the pick up of an adequate supply of material and retains it until it is applied to the eyelashes. It is also important that the filaments that form the bristle ends have sufficient structural strength to comb the material or mascara through the eyelashes.
A conventional mascara brush has a twisted wire core, and a bristle portion. The bristle portion has a plurality of plastic filaments. Each plastic filament is gripped by the twisted wire medially of its ends to form bristle ends.
2. Description of the Prior Art
U.S. Pat. No. 4,887,622 to Gueret is directed to a brush of this type in which the bristle ends extend radially from the core as a helical array and are disposed in a manner to avoid interference of the bristle ends of one turn with the bristle ends of adjacent turns. Each filament has a diameter from 0.10 to 0.25 mm. The number of filaments per helical turn of the twisted wire core is approximately 10 to 40.
U.S. Pat. No. 4,993,440 to Gueret is also directed to a mascara brush that has a twisted wire core, and a bristle portion. The bristle portion has a plurality of plastic filaments. Each plastic filament is gripped by the twisted wire medially of its ends to form bristle ends. This patent also provides that each filament has one or more U or V shaped capillary channels formed in its surface. The sides of the U or V shaped capillary channel converge slightly toward each other near their free ends before again diverging outward to a zone where the channel opens out at the surface of the filament. The bristle ends are disposed to extend radially from the wire core, and are distributed to avoid interference of the bristle ends of one turn with the bristle ends of adjacent turns.
U.S. Pat No. 4,733,425 to Hartel, et al. is directed to a brush of the type described above in U.S. Pat No. 4,887,622. In this Hartel patent, the plastic filament bristle ends flare outwardly in various directions when gripped by the twisted wire. This outward flaring forms a bristle end distribution pattern that is uniform at the bristle face. The filament is described as a hollow or tubular polyamide, or one that has a non-circular cross section.